Evolution of Physiological Variables in Patients with Chronic Obstructive Pulmonary Disease before and during Long-Term Oxygen Therapy

Abstract

In 24 patients with severe chronic obstructive pulmonary disease (COPD), we investigated the evolution of pulmonary volumes, arterial blood gases (ABG) and mean pulmonary artery pressure (PAP), before (T₀-T₁) and during (T₁-T₂) long-term oxygen therapy (LTO). LTO was initiated at T₁ on usual criteria (PaO₂ persistently ≤55 mm Hg) and was given during ≥16 h/day. The T₀-T₁ period ranged from 12 to 186 months (mean 53 ± 41 months) and the T₁-T₂ period from 12 to 120 months (mean 44 ± 30 months). There was a significant worsening of the obstructive pattern (FEV₁ decreasing from 1,084 ± 326 to 879 ± 318 ml, p < 0.005) and of ABG (PaO₂ decreasing from 58.2 ± 9.2 to 51.6 ± 6.5 mm Hg, p < 0.01) before the onset of LTO, whereas there was a rather good stability of ABG during LTO and the changes in pulmonary volumes were modest and statistically nonsignificant (FEV₁ decreased from 879 ± 318 to 809 ± 247 ml). PAP tended to increase from T₀ to T₁ and to decrease from T₁ to T₂, but these changes only reached the level of statistical significance when they were expressed as changes per year ( + 1.0 ± 2.7 vs. –1.3 ± 4.5 mm Hg, p < 0.05). The evolution of physiological variables was nearly identical in subgroups of patients who had died (n = 13) or were still alive (n = 11) at the time of data collection (T₃) and this held particularly true for PAP. However, FΕV₁ at T₂ was significantly lower (p < 0.01) in patients who died. It is concluded that the progressive deterioration of pulmonary volumes, ABG and PAP, which is observed before the onset of LTO is reduced (lung volumes), stopped (ABG) or reversed (PAP) during LTO. In COPD patients under LTO, prognosis is not related to the evolution of PAP or ABG (in ambient air) but rather to the worsening of bronchial obstruction

Effects of intermittent hypoxia on pulmonary haemodynamics: animal modelsversusstudies in humans

“…It seems that breathing oxygen for 14.5 h?day -1 is sufficient to prevent the progression of PH in patients undergoing LTOT. Other authors have reported a reduction of PAP after LTOT [69,70]. Based on these data it seems that short, intermittent episodes of hypoxia do not aggravate PH in severe COPD patients.…”

Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

“… 41 , 42 , 43 , 44 , 45 , 46 As developing economies increasingly experience cardiovascular disease burden, investing in health system infrastructure to ensure access to these interventions as well as to primary prevention therapeutics could help to mitigate disability and improve survival into older ages. 40 , 47 , 48 Chronic respiratory conditions also inflict considerable health loss in older people, contributing to more than 5% of YLDs starting in the 50–54 year age group, globally, who were exposed to risk factors such as smoking and indoor air pollution and similarly pose challenges to health systems with ageing populations, given the importance of oxygen therapy, 49 , 50 , 51 , 52 access to medical care, 53 , 54 , 55 and the risk of respiratory infections among these patient populations. 56 , 57 Neurological conditions continue to show large numbers of prevalent cases and YLDs, with consistent increases in recent years.…”

Pulmonary Hemodynamics in Advanced COPD Candidates for Lung Volume Reduction Surgery or Lung Transplantation

“…S econdary pulmonary hypertension is a wellknown possible feature in patients with advanced COPD. 1,2 The studies [3][4][5] that have focused on this topic have shown that pulmonary hypertension is frequent during exacerbations or exercise but is not constant when the subjects are studied in a stable state of their disease. When present at rest, pulmonary hypertension is in general of moderate severity, but the range of mean pulmonary artery pressures (PAPms) that may be observed is very wide.…”